What is the stratification of coal in the Luchi pressurized gasification furnace, and what are the main physicochemical changes that occur in each layer?

The Ruchi pressurized gasifier is a fixed-bed pressurized gasifier in which coal is primarily divided into a drying layer, a pyrolysis layer, an oxidation layer, and a reduction layer. 1. Drying layer: The preheated air and hot gases at the bottom rise, first causing the coal particles at the top to lose moisture, which is the drying process. 2. Pyrolysis stage: After the moisture is removed from the coal particles, the temperature rises further, and the coal begins to pyrolyze, producing volatiles and semi-coke, along with the release of small molecular gases and tar. 3. Oxidation layer: Below the pyrolysis layer, semi-coke reacts with the oxygen entering the furnace (usually oxygen or oxygen-enriched air), resulting in combustion that releases a large amount of heat, thereby maintaining the temperature inside the furnace. 4. Reduction layer: Below the oxidation layer, the gasification medium (such as steam and oxygen or air) reacts with the high-temperature carbonaceous material (semi-coke) to produce gaseous products such as carbon monoxide and hydrogen; this is the main area for gasification. Inside the gasifier, the physicochemical changes of coal are a continuous process, and there may be overlaps, but the above are the main characteristic reactions at each stage. .